Seam for woven fabric

ABSTRACT

A seam for an endless woven fabric wherein end portions of weft strands project from the ends of the fabric and are woven together in the seam with a plurality of added warp strands so that the warp end portions projecting from one end of the fabric and those from the other end of the fabric to be joined meet at a termination point and these termination points are both laterally and longitudinally spaced from one another.

United States Patent MacBean Oct. 24, 1972 54] SEAM FOR WOVEN FABRIC [56] References Cited [72] Inventor: Donald George MacBean, Pierre- UNITED STATES PATENTS fonds, Roxboro, Quebec, Canada r 926,004 6/1909 Keller ..245/l0 3,335,986 8/1967 Cross ..245/l0 g eez Ltd. Montreal Que e Haller Canada I FOREIGN PATENTS OR APPLICATIONS [22] Filed: Aug. 18, 1971 R11,073 2/1953 Germany.....'. 245/10 Primary Examiner-Richard J. Herbst pp N05 172,864 Att0rney-Alan Swabey Related US. Application Data [57] ABSTRACT A seam for an endless woven fabric wherein end por- [63] fggg t z 2 y tions of weft strands project from the ends of the a an 9 fabric and are woven together in the seam with a plurality of added warp strands so that the warp end per- [30] Forelgn Apphcamm Pnomy Data tions projecting from one end of the fabric and those June 13, 1969 Canada ..o54,34s from the other end ef'the fabric to be joined meet at a termination point and these termination points are [52] U 8 Cl 245/10 both laterally and longitudinally spaced from one [51 int. Cl. ..B21f 27/10 when [5 8] Field of Search ..245/ 10 1 Claim, 6 Drawing Figures P'ATENTEDucI24 1912 I 3.700.194

sum 1 0F 2 //15 //c 06/ g W m INVYENTOR Donald G. MacBEAN ATTORNEY PATENTED BT 24 I97? I 3.700.194 sum 2 or 2 FIG. 4 FIG 5 1 1 6 11 16 21 25 31 1 6 11 16 21 25 31 Warp Warp LNVENTOR Donald G. MocBEAN ATTORNEY SEAM FOR WOVEN FABRIC This application is a continuation of Ser. No. 844,108, filed July 23, 1969, now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an improved seam construction for joining the ends of a woven fabric length to form ablockage area and affect drainage leading to marking of the paper web. With the ends of the warp 7 from one edge joined or terminating alongside the ends form a woven endless belt. The woven endless belt in- 10 corporating the improved seam construction is mainly intended to be used in the paper manufacturing industry for use as a Fourdrinier wire or for other paper web carrying applications in the industry.

2. Description of Prior A11 The woven endless belt is constructed of plastic, metal, or a combination of plastic and metal strands, but it is particularly designed for the use of plastic strands. The strands, comprising the warp and weft threads forming the woven fabric, can be in the form of wire, monofilaments, or thin threads twisted into cable form. The terms warp and weft used throughout are used in the same sense that they are used in the manufacture of a Fourdrinier wire wherein the warp designates the longitudinal or machine direction strands, and the weft, the transverse or crossmachine direction strands. The seam is particularly adapted to be used with a woven fabric length wherein both the warp and weft are crimped during weaving to form knuckles therein as is well known in the art.

It is desirable that theseam in a woven endless belt has certain characteristics, particularly where the belt is used to drain a newly formed paper web in the making of fine paper. For example, the seam construction must have substantially the same drainage properties as the woven fabric length whose end edges it joins so that the web produced has uniform properties. Further, the seam must be constructed in such a manner as to avoid the marking of the web when the web is being drained during transport by the woven endless belt. Each termination point forms a small blockage area affecting drainage. If the seam is formed in such a manner that the joints or termination points of the individual warps extending from the edges of the fabric length are arranged closely adjacent each'other, they can combine to form a large blockage area which during drainage of the web carried by the belt, will cause marking of the finished web. in fine paper manufacture, marking is to be avoided because it spoils the appearance of the paper. The seam further must be constructed to provide adequate strength at the joint to hold the edges of the woven fabric length together. A strong seam is particularly difficult to obtain in the manufacture of plastic endless belts where the warp strands are straightened by heat setting.

Many seam constructions have been proposed and used in the art. One type of scam construction, which provides a seam area substantially the same in appearance as the woven fabric length, comprises warps,

. warps extending from the other edge of the fabric. Normally, this type of seam employing extra or added wefts of the warp from the other edge, small blockage areas are formed, and since a large number of these areas are in a narrow seam, the drainage properties of the seam are not substantially the same as that of the rest of the fabric.

,It is a purpose of the invention to provide an improved seam construction for the joining of the end edges of the woven fabric length to form a woven endless belt which has improved drainage properties,

" added strength and minimizes the marking of a paper I web carried by the belt.

The seam is characterized by being much wider than those that are normallyused in the art. This is as a result of using a large number of added wefts to form the seam with the warps extending from the ends of the woven fabric length. Preferably at least 90 added wefts are used in the forming of the seam. Further, the pattern formed by the termination points of opposed warps is such that they are spaced from one another over the area of the seam so as to minimize marking of the web. The added width of the seam improves the drainage properties of the seam and permits it to drain nearly as efficiently as the woven fabric length. For example, drainage through the seam of the present invention is approximately 95 percent of the drainage through the woven fabric length. The wider seam also produces a stronger joint. The strength of the seam is at least 75 percent of the strength of the woven fabric length.

The improved seam is particularly adapted to be used with a semi-twill weave. This type of weave is well known in the art, particularly in the making of Fourdrinier wires and is generally most suitable in the weaving of plastic fabrics. The semi-twill weave has a construction where a first warp passes under the first and second wefts and over the third and then repeats the pattern. The next adjacent warp passes over the first I weft, under the second and third and then repeats the over one, under two pattern. The pattern is the same for each warp except that each succeeding warp passes under a weft which is adjacent to the weft the foregoing warp passed over and provides a fabric which has a larger web-carrying top surface compared to that provided by a plain weave and also provides a more wear resistant surface on the bottOm of the fabric.

In a semi-twill weave, it is preferred that the ends of the warps extending toward each other from the edges of the fabric length are normally terminated at a weft over which the ends of the warp pass. Since only every third weft is passed over by a warp, the locations at which the termination points of the warps can be located are limited and a specific pattern must be used to provide the proper spacing between the termination points in order to avoid marking of the web.

The invention specifically relates to an endless belt of woven fabric formed from plastic, metal, or a cornbination of both, comprising alength of woven fabric the end edges of which are joined together by a seam. The woven fabric length comprises spaced apart warps woven in a selected repeated pattern with spaced apart wefts. The warps extend from the end edges of the woven fabric length. The seam comprises a plurality of added wefts interwoven with the lengths of warps extending from the edges of the fabric length in the same selected repeated pattern as that of thefabric length. Each end of a warp extending from one edge of the fabric length terminates at a point in the seam adjacent the erid of a corresponding warp extending from the other edge of the fabric length. The termination points form a substantially uniform pattern extending over the seam area whereby no two termination points, formed on adjacent warps, extending from one edge of the fabric length, are closely adjacent each other.

The improved seam is further characterized in that the number of added weft threads is of a sufficient number to provide the seam with a drainage of at least 95 percent of that of the remainder of the woven fabric. Preferably, this is done by providing at least 90 added wefts in the formation of the seam.

The seam is preferably constructed so that any termination point is located at a point in the seam at least strands from the next nearest termination point, said strands comprising either warps, added wefts, or a combination of both, said strands counted from any termination point in the weft direction, the warp direction, or in both the warp and weft directions.

The seam is'particularly useful in a woven endless belt having a semi-twill weave and made of plastic material with the added wefts being pre-crimped.

BRIEF DESCRIPTION OF DRAWINGS The invention will now be described in detail having reference to the accompanying drawings, wherein:

FIG. 1 is a partial plan view illustrating the seam and the ends of the fabric length joined by the seam;

FIG. 2 is a cross-sectional detail view showing the joining of opposite warps when the seam is formed in a semi-twill weave;

' FIG. 3 is a schematic detail view showing one method of forming the termination point of warp ends in a seam having a semi-twill pattern;

FIG. 4 is a graphical representation of one pattern preferably for use in joining the warp ends of the seam having a semi-twill pattern;

FIG. 5 is a second pattern suitable for joining the warp ends of the seam having a semi-twill pattern; and

FIG. 6, appearing on the same sheet as FIG. 1, is a detail view showing a second method of forming the termination point of warp ends in a seam having a semitwill pattern.

DESCRIPTION OF PREFERRED EMBODIMENTS FIG. 1 shows a portion of a woven endless belt 1 with the improved seam 3. The seam is located between the end edges 5 and 7 of the woven fabric length 9. The fabric length shown in FIG. 1 comprises a plurality of spaced apart warps 11A, 11B, etc. extending longitudinally of the fabric length and a plurality of spaced apart wefts 13A, 13B, 13C, 13D, etc. woven together in under and over fashion to form a plain weave. While a plain weave pattern has been shown, it will be obvious that other well-known patternsin the paper making weaving art can be used. One end portion 15A, 158, etc. of the warps 11A, 118, etc. extend from one end edge 5 of the woven fabric length toward the other end portions 17A, 178, etc. of the warps 11A, 118, etc. extending from the other end edge 7.

The seam is formed by'incorporating a plurality 0 added wefts 19A,19B, etcrinto the space between the edges of the fabric length and interweaving them with the end portions 15A, 15B, etc. and 17A, 178, etc. of the warps extending from the edges of the fabric length, in the same pattern as the woven fabric length, which in this example, is a plain weave. Each end of a warp end portion from one edge'terminates adjacent the end of the corresponding warp end portion extending from the other edge at a termination point. For example, the end of warp end portion 15A terminates adjacent warp end portion 17A at termination point-21A asshown by an X in FIG.v 1. The termination points 21A, 218, etc. for each pair of corresponding warp end portions must be spaced from one another or distributed over the area of the seam 3 to avoid marking a newly formed paper web carried by the endless belt during drainage as previously discussed. Any pattern wherein a termination point is a count of at least 10 strands from the next nearest termination point; wherein the strands can comprise either warps 11, added wefts 19, or a combination of both, and are counted in either the weft direction, the warp direction, or a combination of both directions from the termination point to the next nearest one; is used to space the termination points from one another.

The spacing is obtained partially'by inserting a large number of added weft threads 19 to form the seam 3 contrary to the normal practice of inserting as few as possible. Preferably, at las'ta minimum of 90 added wefts are used to form the seam. The reason for using so many added wefts is to have drainage through the seam area which closely approximates the drainage through the remainder of the belt. Each termination point blocks a minute area of the seam. The total area blocked is fixed for any one fabric length in depen dence on the number of warps used. Since the blocked area of the seam is constant, the drainage capacity of the seam can be increased only by increasing the width (in the machine direction) of the seam. Theoretically, the seam can be made as wide as possible so that thousands of added wefts could be used. However, it is costly to weave the seam using the extending warp portions and added wefts. The cost increases with the number of added wefts used. Therefore, a compromise must be reached between cost and satisfactory drainage in the number of added wefts used. The number should range between 90 and 120. The use of 90 added wefts provides good drainage qualities and also provides a sufiiciently large area in which to space the termination points from each other to avoid marking of the seam. In FIG. 1, 90 added wefts are used to form the seam. Each succeeding termination point 21 is spaced 14 wefts from the preceding point. If the first point 21A is formed on the first added weft 19A, the second point 21B will be'formed on the 15th added weft, the third point 21C on the 29th added weft, and so on. The seventh point, 21G, is formed on the th added weft. The eighth point, 21H, is formed on the ninth addedweft, and the pattern is repeated across the length of the seam. Each termination point 21 is spaced from the other by a count of at last strands. Thus, point 21H is a count of strands (7 warps and 8 added wefts) from point 21A.

Since the termination points are spaced from each other, the seam is stronger and more closely approaches the strength of the woven web. The added wefts 19 in the seam are spaced apart the same distance as the wefts 13 in the woven fabric length.

If the woven fabric length is crimped to form knuckles in both the warp and weft directions during weaving, the added wefts 19 can also be crimped in the same pattern as the wefts 13 in the woven fabric length to provide a uniform structure and appearance between the seam and the woven fabric length.

The added crimped wefts 19 can be obtained by weaving the fabric length 9 and then stripping off the wefts 13 from both ends. This leaves the warps 15, 17 extending from the newly-formed end edges 5, 7 of the fabric length. The removed wefts 13 are then inserted into the space between the edges as the added wefts 19, and the warp ends are interwoven between the added wefts in the same pattern as the woven fabric length to form the seam. The warps are cut off or joined at the termination points after the weaving operation. When the woven fabric length is of plastic material and crimped during weaving, the woven fabric length is normally heat set prior to stripping off the wefts to form the added wefts and the crimp stays in both the added wefts and the warp end portions. When the added wefts are interwoven with the warp end portions, they easily lock in place in the same pattern as the woven fabric length due to their crimping. I

The termination points 21 in the seam can be forme in a particular manner. In weaving the seam, each warp The semi-twill weave provides a good supporting surface for the web and also a wear resistant undersurface for the woven fabric. The warp ends are preferably finished at atermination point where they pass over a single weft in the same manner as shown in FIGS. 2 and 3. In a plastic fabric length incorporating the semi-twill weave, the warp and .weft threads are crimped and then heat set, and the required number ofadded wefts are stripped from the ends of the woven fabric. The added wefts are then woven in the same semi-twill pattern with the warps extending from the end edges of the fabric length to form the seam. The warp ends terminate in a pattern on the seam area such that they are end portion '15, 17 is woven with the weft to its preselected termination point 21 located at one of the added wefts 19. At the added weft, as shown in FIGS. 2 and 3, which illustrate a semi-twill weave to be described in detail later, the unused part of the warp end portions 15, 17 are cut off in such a manner as to form a hook portion 23, 25 extending over the added weft from each warp end portion. The hook portions are formed due to the crimp in the warps during weaving. Each cut end 27, 29 of the hook portion extends down away from the top or webcarrying surface 31 of the seam to lie flush with the bottom of the cloth as shown in FIG. 2 and thus provide a smooth top surface. Each cut end 27, 29 blocks a portion of an opening 31 in the weave forming the minute blockage area at each termination point as previously discussed. The hook portions 23, 25 are located adjacent each other at the termination point 21. Using this inherent hook construction, the warp end portions need not be joined together as is sometimes necessary in seam constructrons.

While the seam has been described to join end edges of one fabric length, it may also be used to join the end edges of two different fabric lengths to obtain a single fabric length of extended length rather than a closed loop.

The invention is particularly adapted to be used with either left hand or right hand semi-twill weave patterns. A semi-twill weave pattern is shown in FIGS. 2 and 3.

spaced apart from one another so as to avoid marking. Since it is desirable to have the ends of the warps turned inwardly at the termination points to provide a smooth web-carrying surface, each termination point should be formed on every third weft for any one warp. Thus, specific patterns are required in order to obtain the necessary spacing of the termination points from each other and to locate each termination point at a weft over which the warp passed. Again, the number of added wefts is at least in order to provide drainage for the seam similar to that obtained by the fabric itself.

A, preferred pattern for spacing the termination points in the semi-twill weave is shown in FIG. 4 wherein I07 added wefts are used to form the seam. For each succeeding warp, itstermination point is spaced 23 wefts from the preceding warp termination point. The vertical portion of the pattern shows the 107 wefts added between the edges of the fabric length, and the horizontal portion shows 31 warp ends extending from each edge of the fabric length. The No. 1 warp ends terminate at the No. 1 added weft, which weft extends under the warps. The termination point is designated by an X and is similar to that shown in FIGS. 2 or 3. The No. 1 warp passes over the No. 1 weft, under Nos. 2 and 3, over No. 4, under Nos. 5, 6, over No. 7, etc. The No. 2 warp in the semi-twill pattern passes under the Nos. 1 and 2 wefts, over No..3,-under Nos. 4, 5, over No. 6, under Nos. 7, 8,.et'c. The ends of No. 2 warp terminate at added weft No. 24 where they pass over this added weft. Similarly, the No. 3 warp ends are joined together on weft No. 47, No. 4 warp is joined on weft 70, and No. 5 warp on weft 93. This constitutes one run across the seam width. The pattern is then repeated in a second run whereby No. 6 warp terminates on No. 8 weft at which point again it passes over this weft. The No. 7 warp terminates on weft 31, the eighth on weft 54, the ninth on weft 77, and the 10th on weft 100, eight wefts from the top. The third run is begun where the eleventh warp terminates on weft 15 starting from the bottom, the 12th at 38, the 13th at 61, the 14th at 84, and the 15th at 107, the'last added weft. The pattern of termination points for the first fifteen warps can now be repeated for the next 15 warps where the warp ends for the 16th warp terminate at the first added weft, the 17th warp terminates at the 24th weft, etc. The same pattern can be repeated for each succeeding group of 15 warps across the seam. The resultant seam with the termination points in the pattern as shown in FIG. 5 reveals a substantially diagonal pattern with substantially linear rows extending in one direction and other substantially linear rows extending in a transverse direction to the first rows to located a total of seven wefts plus five warps for a total of 12 strands from the next nearest adjacent termination points asshown to provide adequate spacing.

While the pattern in FIG. 4 has five termination points in each run across the seam when using 107 added wefts, and a repeat pattern every three runs, six or seven termination points may be joined in one run across the seam, particularly if a wider seam is made using more than 107 added wefts. I A further pattern for semi-twill weave is shown in FIG. 5 wherein 20 weft spacing is used between adjacent termination points and ,109 added wefts are used. Again, in the semi-twill weave, warp No. 1 passes over the first weft,- under the next two, over the fourth, under the next two, over the seventh, etc. The No. 2 warp passes under wefts one and two, over three, under four and five, over six in a repeat fashion'so that for each adjacent warp, it passes over a weft which is one less in number than the weft previously passed over. In this embodiment, the first termination point is at 1, 1, the second 2, 21, etc. in a repeat pattern across the length of a seam. I

In still another pattern, proper spacing between the termination points using 101 added wefts and a23 weft spacing between the first and second warps, 20

' terns described since one complete pattern is obtained using only 15 warp ends and then the identical pattern can be repeated for each succeeding group of 15 warp ends. The other patterns do not, if at all, repeat as readily. In being able to use a short repeated pattern, the selector mechanism, used to aid in cutting the warp ends at the correct locations to form the termination points, is simpler to make and to use and the seam is easier to make.

While one method of forming the termination points between the warp ends has been shown in FIGS. 2 and 3, for use in a crimped, plastic semi-twill weave, an alternative method is shown in FIG. 6 wherein a single vertical cut is made on the end portions 15, 17 of the warp 1 l at the termination point 21. Because the warps 8 are pre-crimped and of plastic, they have resiliency and snap in place abutting one another at their cut ends 33 so as to form an extremely neat termination point and avoid blocking openings in the fabric. However, this method of joining is not preferred because the abutting ends can work loose from one another and slip off the weft over which they pass thus forming gaps in the seam area whichagain leads to marking of a web.

In one preferred embodiment incorporating the seam of the present invention, warps of 0.01062 in. diameter were interwoven in a semi-twill weave pattern with wefts of 0.0138 in. diameter to provide a fabric having a mesh of 50X 36/inch. This seam had 107 added wefts interwoven with the warp ends in the pattern shown in 4-w1th a spacmg of 23 wefts between each adjacent warp termination point for every run of three across'the seam width. The seam hada strength of approximately percent of the woven fabric. When tested for drainage at k inch water pressure through a 1 inch diameter orifice, the semi-twill I woven fabric length drained at 500 cubic feet of air per minute per square foot of areawhereas the seam drained at 475 cubic feet of air per minute per square foot of area thus providing a 5 percent difference in drainage between the seam and the woven fabric.

I claim: I 1. A seam joining theends of a woven fabric, said fabric comprising spaced apart warps interwoven in a semi-twill weaving pattern with spaced apart wefts,

warp end portions projecting from said ends of said fabric and terminating in free ends, the seam including 107 added wefts interwoven with said warp end portions in the same semi-twill pattern as that of said fabric, the free end of each said warp end portion projecting from one end of said fabric terminating at a point in said seam located over a weft and adjacent said free end of a warp end portion projecting from the other end of said fabric located over the same weft, said termination points arranged in a repeat pattern repeated for each group of 15 warps and wherein each succeeding termination point in said repeat pattern is spaced twenty-three wefts from the termination point in a preceding warp, said termination points being arranged in a substantially uniform pattern over the whole area of said seam, with each of said termination points spaced from the nearest adjacent termination point by a total count of at least- 10 warp and weft strands. 

1. A seam joining the ends of a woven fabric, said fabric comprising spaced apart warps interwoven in a semi-twill weaving pattern with spaced apart wefts, warp end portions projecting from said ends of said fabric and terminating in free ends, the seam including 107 added wefts interwoven with said warp end portions in the same semi-twill pattern as that of said fabric, the free end of each said warp end portion projecting from one end of said fabric terminating at a point in said seam located over a weft and adjacent said free end of a warp end portion projecting from the other end of said fabric located over the same weft, said termination points arranged in a repeat pattern repeated for each group of 15 warps and wherein each succeeding termination point in said repeat pattern is spaced twenty-three wefts from the termination point in a preceding warp, said termination points being arranged in a substantially uniform pattern over the whole area of said seam, with each of said termination points spaced from the nearest adjacent termination point by a total count of at least 10 warp and weft strands. 